It is known that 2,2-difluoroacetaldehyde, which is represented by the formula (1), is a compound useful as a raw material for production of advanced materials or an intermediate for production of pharmaceutical and agrichemical products.CHF2—CHO  (1)In particular, 2,2-difluoroacetaldehyde has a difluoromethyl group (—CHF2) in which two fluorine atoms of high electronegativity and one hydrogen atom are bonded to the same carbon atom. It is considered that this specific structure is deeply relevant to the properties of various materials produced therewith, such as water repellency, transparency, low dielectric constant, peculiar physiological activity and mimic effect. Consequently, materials produced using 2,2-difluoroacetaldehyde as building blocks are becoming subjects of vigorous researches and developments in the fields of advanced materials and pharmaceutical and agrichemical intermediates.
For example, Patent Document 1 proposes the use of 2,2-difluoroacetaldehyde as a raw material for production of hydroxyl carbonyl halides useful as pharmaceutical and agrichemical intermediates. Patent Document 2 proposes the use of 2,2-difluoroacetaldehyde as a raw material for production of novel insecticides.
There is conventionally known a method of synthesizing 2,2-difluoroacetaldehyde by partial reduction of an α,α-difluoroacetate with a hydride reduction agent such as lithium aluminum hydride (see Non-Patent Document 1). By contrast, the present applicant has filed a patent application based on the findings that it is possible to synthesize 2,2-difluoroacetaldehyde by contact of an α,α-difluoroacetate with hydrogen (H2) gas in the presence of a specific ruthenium complex as a catalyst (see Patent Document 3).
On the other hand, it is known that an aldehyde is unstable and loses its aldehyde activity due to gradual polymerization of aldehyde molecules (see Non-Patent Document 2). Thus, proposed is a method of preventing polymerization of an aldehyde by providing the aldehyde in aqueous solution (hydrate) form and mixing therewith a specific surfactant, a pH modifier and a buffer (see Patent Document 4). Also proposed is a method of converting an aldehyde to a stable acetal by contact with a large excessive amount of alcohol (see Non-Patent Document 3).